The end of a long exposure cuts off the flight path of a small plane mid-way over Portland Water Bureau's open Reservoir 6 in Mount Tabor Park. This is one of three open reservoirs at Mt Tabor Park and of five total in Portland. The 3 open reservoirs in Mount Tabor Park were placed in the National Register of Historic Places on January 15, 2004. Environmental Protection Agency (EPA) regulation: Long Term 2 Enhanced Surface Water Treatment Rule, referred to as the LT2 rule imposes new requirements that open water reservoirs be covered, buried or additionally treated. This applies to Portland's five open reservoirs and to the unfiltered Bull Run sourse supplying them. Photo: July 2011. Nikon D700, 20-35/2.8D.